Conveyor belt filter devices of the kind mentioned above are also known as so-called paternoster filter rakes and primarily serve to mechanically clean flowing waste water in channels formed for this purpose. The waste water flows transversally through the filter elements or also in the longitudinal direction of the filter elements and the latter carry the filtrate, which cannot pass the filter elements, out of the channel. In the area of an upper deflection device of the filter belt, said deflection device being arranged above the waste water surface, a wiper device is provided, which is implemented as a rotating brush, for example, and which removes filtrate sticking to the filter elements from the filter elements in a wiping process before they again dive into the liquid flowing through the channel in the course of the circulation of the filter belt. Since the effectiveness of the wiping process depends for a large part on the contact force with which the wiper device bears against the filter elements and because it is substantial for avoiding excessive wear to set the contact force as low as possible, it is substantial for the desired smooth operation of a conveyor belt filter device to allow for an optimal setting of the contact force and to provide for corresponding adjusting means at the wiper device and at the conveyor belt filter device.
Besides the adjustments or changes to the setting of the contact force which become necessary because of unavoidable wear in the course of the operation of the wiper device, adjustments of the wiper device also become necessary when a change of the center distance between the deflection devices of the conveyor belt is required because of a wear of the flexible driving means of the conveyor belt filter device and a corresponding elongation of the driving means.